FEEDING STANDARDS: ORIGIN AND USE 277 



ferent animals, and had learned much of the digestibility 

 of feeds. His studies resulted in what are now known as 



The Wolff feeding standards for farm animals. Two 

 things were shown by this great scientist. One was the 

 digestibility of the nutrients in different feeding stuffs, and 

 the other was the amount of each of these required by farm 

 animals under certain conditions. Wolff found that ani- 

 mals that were doing no labor, that were not being fattened, 

 neither gaining nor losing in weight, required only sufficient 

 food to keep the body and the internal organs healthy and 

 vigorous. Such an animal required what he called a main- 

 tenance ration. A young animal needed a growing ration, 

 and cattle intended for meat required a fattening ration. 

 A cow producing a large amount of milk must be fed, first 

 to supply the ordinary needs of the body, such as might be 

 found in a maintenance ration, and besides this, she must be 

 fed still more to enable her to produce the milk of which the 

 food is the source. The dry cow may be satisfied on a 

 maintenance ration consisting of some form of roughage 

 only, such as clover hay for example; but if she is yielding a 

 good supply of milk, then rich concentrates must be fed, if 

 the increased demands of milk production are to be met. 



Since Wolff first made known this most important dis- 

 covery, many other chemists have experimented in the same 

 field. Both European and American agricultural chemists 

 have studied the science of feeding, so that now we know 

 much more than did the student or farmer in the days of 

 Wolff. Animals have been carefully studied, and the inven- 

 tion of the respiration calorimeter has resulted in some 

 wonderful investigations in the fields of chemistry and 

 animal nutrition. The work of Wolff was that of a pioneer. 

 For many years Americans relied on analyses of German 

 feeds, and made use of the standards that came to us from 



